1. FIELD OF THE INVENTION
This invention relates to energetic oxidizers for solid propellants, and more specifically to an oxidizer for use in minimum smoke solid propellant systems.
2. DESCRIPTION OF THE PRIOR ART
Current solid propellant formulations use as the oxidizer, primarily, ammonium perchlorate (AP) and/or HMX. For minimum smoke propellants, where the plume signature is important, HMX is the oxidizer of choice, since HCl liberated from AP produces a very smoky exhaust. HMX, with an empirical formula of C.sub.4 H.sub.8 N.sub.8 O.sub.8 is balanced to CO and H.sub.2 O. Since HMX is just balanced as a monopropellant, an oxygenated binder system, such as nitrocellulose/nitroglycerine, is required for use with it in order to maintain moderate propellant performance. To increase the performance potential of the oxidizer, there are two possibilities: (1) increase the positive heat of formation and/or (2) increase the oxygen content while maintaining a reasonably favorable heat of formation. The oxygen must primarily be incorporated as energetic nitro groups, since oxygenated functions such as esters and ureas have a deleterious effect on the heat of formation of the molecule.
Other property goals, besides high oxygen balance (high O/C), that must be included for an oxidizer candidate are high density, melting point greater than 100.degree. C., and acceptable thermal stability and impact sensitivity. Of particular importance is the high density of the oxidizer, which controls the density impulse of the propellant system. HMX is unique among energetic organic compounds with a density of 1.90 g/cc. This property is one of the prime reasons for the attractiveness of HMX as an oxidizer. However, its low oxygen balance (O/C=2.0) restricts the overall energy of HMX propellant systems.